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Registered
Join Date: Sep 2013
Location: Clayton, NC
Posts: 277
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PMOs on a 3.0L
Perhaps the brain trust can help.
It’s a 3.0L with Solex cams and about 11:1 compression. MSD ignition system. AND 46 PMOs supposedly jetted for a 3.0L It runs very rich and generally fouls the plugs within a few miles It then becomes undriveable Anyone have a similar setup, what jets work for you? What else might be missing in this puzzle? I believe it is improperly setup, when compared to a similar Weber carb setup as documented in the Performance Oriented tech pages, none of the jets / emulsion tubes / venturis match. Theses are PMOs not Weber’s but you would believe them to be close. I’m asking for a friend who is at the end of his wits at solving this problem Thanks in advance |
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06-11-2021, 08:21 AM
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I would rather be driving
Join Date: Apr 2000
Location: Austin, TX
Posts: 9,108
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Does the car run well if you can get past the start-up phase?
Was the idle mixture properly adjusted? Are the carbs well sync'd across all 6 throats? What is the jetting in there now? Hard to say if they are too large or too small... Is the engine twin plugged? Both sets of plugs working? What plugs are installed? Heat range? It is typical to go to a slighter hotter plug range with carbs compared to CIS/Motronic.
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Jamie - I can explain it to you. But I can not understand it for you. 71 911T SWT - Sun and Fun Mobile 72 911T project car. "Minne" - A tangy version of tangerine #projectminne classicautowerks.com - EFI conversion parts and suspension setups. IG Classicautowerks |
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06-11-2021, 08:24 AM
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Join Date: Sep 2013
Location: Clayton, NC
Posts: 277
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No, it apparently does run well very long past start up. Accelerates well and supposedly lots of power at high throttle settings but fouls out at more normal driving power settings
Idle mixture set and synchronized across all six throats Not twin plugged. Plugs have been changed to higher heat range and tried Iridiums too. I’ll will get the hear range Jets installed by PMO for this engine setup. I don’t have the numbers. I’ll will get them. But as I noted, they don’t match Abbott’s jetting chart in his tech pages. |
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06-11-2021, 08:43 AM
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Registered
Join Date: Sep 2013
Location: Clayton, NC
Posts: 277
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I didn’t state clearly. It does not run very well once past start up especially at lower rpms
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06-11-2021, 08:47 AM
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Registered
Join Date: Sep 2013
Location: Clayton, NC
Posts: 277
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79 Row 3.0 heads (large ports)
JE 9.5 Compression Ratio pistons Solex cams 46 PMOs 36 Venturi 145 Mains 55 Idles 130 Idle Air 190 Airs F111 Emulsion tubes SSIs with stock exhaust Clewett Wires and MSD Recurved Distributor I earlier statement about 11:1 compression was incorrect. |
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06-11-2021, 09:43 AM
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I'm running 46mm PMOs
2.8, J&E 9:5.1 pistons, Mod S cams, 40mm ports,RSR headers, 997 GT3 muffler. MSD Ignition, Clewett wires,NGK BPR7ES plugs on Single plug heads 38mm Venturis 155 main jets 175 main airs 55 Idles 110 Idle airs F16 emulsion tubes Car runs good, pulls smooth all the way to 6500 Big help from Mr. Parr. Last edited by 911 SLANT; 06-11-2021 at 11:49 AM.. |
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06-11-2021, 10:48 AM
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Check fuel pressure, might be to high and the bowls are filling up. Also check the floats and make sure they are closing and adjusted properly.
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06-11-2021, 05:11 PM
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Join Date: Sep 2013
Location: Clayton, NC
Posts: 277
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Yes, float levels are correct and fuel pressure is correct per PMO
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06-11-2021, 06:06 PM
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It could also be dirty jets. You can pull them and clean them.
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06-11-2021, 08:12 PM
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Stella
